Articles of footwear usually include an upper, a midsole, and an outsole. The upper can include sections of thin material, straps, or the like for securing the footwear to the wearer's foot. The outsole is typically a unitary piece of relatively high-friction material that provides traction for the footwear. Also, the midsole can include foam for providing cushioned support for the wearer.
In some cases, the midsole can even include a bladder that contains a fluid, such as a gas or gel. The weight of the wearer and other loading on the bladder causes the fluid to displace within the bladder. As such, the bladder can more easily resiliently deform and/or more easily conform to the wearer's foot than some midsoles made entirely out of foam. Thus, the midsole can provide improved resiliency for better support of the wearer's foot. Also, the footwear can be more comfortable to wear.
Although conventional footwear with bladders have been adequate for their intended purposes, they do suffer from certain disadvantages. For instance, many bladders include relatively wide, open cavities. Thus, fluid within the cavity flows unimpeded toward lower pressure areas when a load is applied to the bladder. As such, the fluid may be displaced so that it is not providing adequate support for the wearer.
Also, these bladders are often blocked from view by either the outsole or foam material of the midsole. As such, the wearer may not be aware that the footwear includes a bladder. Also, the bladder is unlikely to improve the aesthetics of the footwear. In some cases, the foam material of the midsole and/or the outsole includes an opening so that the bladder is visually exposed. However, the opening is typically small, and only a portion of the bladder can be viewed. Also, in these types of footwear, the bladder is typically unadorned or aesthetically dull. Thus, the footwear is not likely to be improved aesthetically by the bladder.